JP2001177257A - Holing method fort build-up multiplayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method of through-hole and/or blind via hold of small diameter to provided a high-density printed wiring board, using a multilayer capper-plated board as at least a laminating prepreg base material of build-up printed wiring board which comprises a glass non-woven fabric superior in homogeneity and surface smoothness, etc. SOLUTION: A multilayer board is provided as a lamination prepreg which, with a glass fabric base material copper-plated laminated bare used, comprises a glass fiber nonwovn fabric which comprises an oblate glass fabric, by 90 wt.% or higher, with oblateness 3.1/1-5/1, cross section area being 90-98% of a rectangle circumscribing the cross section of glass fabric, and reduced fabric diameter of 5-17 μm. Related to opening a hole of 80-150 μm in diameter on the multiplayer board, a holing assisting layer is formed on a copper foil, which is irradiated directly with a high-output carbon dioxide gas laser selected from among 20-60 mj/pulse to work/remove the cooper foil, forming a through-hole and/or blind via hole. Thus a printed wiring board is provided which is superior in positional accuracy of holds, productivity, reliability in hold connection, and surface smoothness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drilling holes in a build-up multilayer printed wiring board using a novel glass fiber nonwoven fabric at least as a surface layer. More particularly, the present invention relates to a method for forming a hole for a high-density printed wiring board having a small-diameter hole and a fine circuit formed on the surface. This high-density printed wiring board is mainly used for small and new semiconductor plastic packages and the like.

[0002]

2. Description of the Related Art Conventionally, a high-density glass cloth base multilayer printed wiring board used for a semiconductor plastic package or the like has used a glass fiber woven cloth. The multilayer printed wiring board using this glass fiber woven fabric has large irregularities in the hole wall due to the difference in the degree of processing between the glass woven fabric and the resin layer when small holes are made with a carbon dioxide laser. However, the surface irregularities are insufficient for forming a fine circuit. Conventionally, there has been no example of using a glass fiber nonwoven fabric as a build-up material, and no flat glass fiber nonwoven fabric has been used. or,
Conventionally, a through hole was drilled. In recent years, the diameter of drills has become increasingly smaller, and the hole diameter has become 150 μm or less.When drilling such small diameter holes, the drill diameter is small, so the drill bends, breaks, and the processing speed is slow when drilling. However, there have been problems such as productivity and hole connection reliability. In addition, a hole of the same size was made in advance by using a negative film on the front and back copper foils in a predetermined manner using a negative film. If a carbon dioxide laser is used to form a through hole that penetrates the front and back, there are disadvantages such as misalignment of the inner copper foil, misalignment of the upper and lower holes, poor connection, and the inability to form front and back lands. Was.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for forming a small-diameter hole in a new-build-up multilayer printed wiring board having a novel structure which significantly improves the above-mentioned disadvantages.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a glass fiber having a flat cross-section, a flattening ratio expressed by a long diameter / short diameter of the cross-section of 3.1 / 1 to 5/1, and a cross-sectional area of the glass fiber. 90 to 98% of the area of the rectangle circumscribing the glass fiber cross section, the flat fiber having a converted fiber diameter of 5 to 17 μm contains 90% by weight or more,
And a layer in which the thermosetting resin composition is adhered to a glass fiber nonwoven base material having a binder amount of 3 to 8% by weight, and a carbon dioxide gas laser is applied to the surface of the build-up multilayer copper-clad board at least in the form of a surface layer. A method for forming a through-hole and / or a blind via hole by arranging a hole-forming auxiliary layer and irradiating a predetermined number of shots of a high-energy carbon dioxide gas laser from above the layer by pulse oscillation. According to the hole forming method of the present invention, the through holes and the blind via holes formed by the carbon dioxide gas laser have good, uniform hole shapes and excellent hole connection reliability. Further, according to the present invention, by using the above-mentioned glass fiber nonwoven fabric, a material excellent in surface smoothness and excellent in warpage can be obtained.
Furthermore, the homogeneity of the perforated hole wall can be further improved by adding 10 to 80% by weight of the insulating inorganic filler to the thermosetting resin.

In the case of drilling holes having a small diameter of about 100 μm, it is preferable to drill holes using a carbon dioxide gas laser. In this case, the copper foil at the locations where the holes are to be drilled is removed in advance by irradiation with low-energy carbon dioxide laser energy. It is also possible to form a blind via hole. However, in the present invention, a drilling auxiliary layer is formed on the copper foil of the multilayer copper-clad board, and a carbon dioxide gas laser having sufficient energy for processing the copper foil is directly irradiated from above to form a through hole and /
Alternatively, a method in which a blind via hole is formed and a high-density printed wiring board is formed using the blind via hole is employed. This drilling method is excellent in workability, automatically compensates for dimensional shrinkage of the inner layer, the processing speed is much faster than mechanical drilling, and the connection reliability of the obtained small diameter hole is also excellent. This is a significant improvement over the conventional drilling method.

[0006] In order to form a circuit of higher density, by dissolving and removing copper foil burrs generated around the holes and simultaneously dissolving and removing part of the copper foil on the front and back sides in the thickness direction, the subsequent copper plating is performed. The copper foil thickness can be kept thin, and a high-density printed wiring board can be produced. The thermosetting resin used for the multilayer copper-clad board is preferably a multifunctional cyanate compound, a multilayer obtained by using a resin composition containing the cyanate ester prepolymer as an essential component. The printed wiring board is excellent in electrical insulation resistance after migration, migration resistance, heat resistance, and the like.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to a glass fiber having a flat cross section and a flattening ratio expressed by a major axis / a minor axis of the cross section of 3.1 /.
1 to 5/1, the cross-sectional area is 90 to 98% of the area of the rectangle circumscribing the glass fiber, and the reduced fiber diameter is 5 to 17.
A layer in which the thermosetting resin composition is attached to a glass fiber nonwoven fabric base material containing 90% by weight or more of flat glass fibers that are μm and the amount of the binder is 3 to 8% by weight was used at least on the surface layer side. Using a glass cloth base thermosetting resin multilayer copper clad board, an auxiliary layer for carbon dioxide laser drilling is placed on the copper foil on the surface layer, and carbon dioxide gas with sufficient energy to process the copper foil from above This is a method of forming a small diameter through hole and / or a blind via hole by irradiating a laser. A multilayer printed wiring board, preferably a build-up multilayer printed wiring board, is prepared using the perforated multilayer copper-clad board.

In the present invention, the flat glass fiber is defined as having a flatness ratio, that is, a ratio of major axis / minor axis of 3.1 / 1 to 5/1, preferably 3.5 / 1.5.
1 to 4.5 / 1. When the flatness is less than 3.1 / 1, the short diameter is large, so the thickness of the nonwoven fabric is reduced, and the effect of increasing the glass fiber content in the laminate is not sufficient. Glass fibers are difficult to manufacture, and the speed of impregnation of the resin of the varnish is also slow, which tends to cause impregnation failure. Furthermore, the flat glass fiber used in the present invention has a cross-sectional area of a rectangular area circumscribing the cross-section of the glass fiber.
90-98%. That is, the shape is almost rectangular. By using this fiber and making paper using 3 to 8% by weight of a binder, the fiber can be overlapped with the flat surface up and down, the thickness can be reduced, and the surface smoothness when laminated and formed is excellent Is obtained. In the present invention, the converted fiber diameter is
It means the diameter when the cross-sectional area of the fiber is converted into a circle.
The composition of the flat glass fiber used in the present invention is E glass, T
Glass, D glass, and the like that can produce flat glass fibers can be used. Although the glass fiber nonwoven fabric of the present invention is used solely as flat glass fiber, papermaking may be performed using glass fiber having a partially circular cross section.

The glass fiber nonwoven fabric of the present invention is impregnated with a varnish made of a thermosetting resin composition and dried to prepare a B-stage prepreg, which is used as a multilayer board, especially for build-up. The resin content is generally
40 to 60% by weight. For lamination, the resin content is generally 60 to 85% by weight.

In the present invention, a method for forming through-holes and / or blind via holes of 80 to 150 μm in diameter in a build-up printed wiring board prepared by using a prepreg made of a special flat nonwoven base material as a laminated material at least on the surface layer is used. A method using a laser is adopted. An excimer laser or a YAG laser can be used to form a hole having this diameter, but a carbon dioxide gas laser is superior in terms of processing speed, workability, and the like. Further, mechanical drilling has problems such as a low drilling speed and bending of the drill. In particular, in the case of via hole drilling using a carbon dioxide gas laser, a conventional method of irradiating a low energy carbon dioxide laser energy by previously etching and removing the surface copper foil can also be used, but the dimensional accuracy of the baked film is problematic. And it is difficult to form a fine circuit. Therefore, on the multilayer copper-clad, subjected to metal oxide treatment or chemical treatment, or as an auxiliary layer melting point 900 ° C. or more, and a metal compound powder having a binding energy of 300 kJ / mol or more, carbon powder or metal powder and organic matter, Preferably, a paint mixed with a water-soluble resin composition is applied to form a coating film or, on one side of a thermoplastic film, a perforation obtained by adhering the resin composition to a total thickness of 30 to 200 μm. The auxiliary sheet is arranged, preferably laminated and adhered to the copper foil surface, and directly irradiated with a carbon dioxide gas laser from above the auxiliary layer to process and remove the copper foil, thereby forming through holes and / or blind vias. Holes can be formed. It is preferable to use the auxiliary sheet for laser drilling by bonding it to the copper-clad multilayer board at the time of drilling. Lamination is performed by laminating the sheet on a copper-clad multilayer board with the resin attached side facing the copper foil side and heating and pressing, or after pre-wetting the resin surface layer 3 μm or less with moisture, and then room temperature And laminate to the surface under pressure. By making the adhesion of the auxiliary sheet to the copper foil surface good, a good hole shape can be obtained.

After the hole is formed, burrs are generated on the front and back surfaces and the inner layer of the copper foil. Therefore, an etching solution is sprayed or the inside of the hole is sucked and passed to dissolve and remove the burrs of the copper foil generated in the hole. At the same time, when the copper foil is thick, the copper foil on the front and back is partially dissolved and removed in the thickness direction, preferably 2 to 7 μm in thickness, more preferably 3 to 7 μm.
５5 μm. When the copper foil is thin from the beginning, only the burrs are etched away while leaving the auxiliary layers formed on the front and back sides, and then the auxiliary layers are removed. Then, the entire board is copper-plated by a standard method, and a circuit is formed to form a printed wiring board.

In the present invention, the multilayer copper-clad board is a multilayer copper-clad board having at least three or more copper layers. The inner layer plate forms a circuit using a glass woven fabric and / or a non-woven fabric base copper-clad board, performs a surface treatment as necessary, and arranges a flat glass fiber base thermosetting resin prepreg on at least one surface thereof, A copper foil is placed on the outside, and lamination molding is performed under heat, pressure and preferably under vacuum. Also, when creating a high-density circuit, use a thin copper foil from the beginning, or laminate a thick copper foil, and then etch the surface copper foil with an etchant to 2 to 7 μm. Thinner can be used. When a thin copper foil is used from the beginning, a copper foil with a carrier such as copper or aluminum is mainly used.

As the resin of the thermosetting resin composition of the copper clad board used in the present invention, generally known thermosetting resins are used. Specifically, an epoxy resin, a polyfunctional cyanate ester resin, a polyfunctional maleimide-cyanate ester resin, a polyfunctional maleimide resin, an unsaturated group-containing polyphenylene ether resin, and the like, and one or more kinds Are used in combination. From the viewpoint of through-hole shape in processing by high-output carbon dioxide laser irradiation, a thermosetting resin composition having a glass transition temperature of 150 ° C or higher is preferable, and has moisture resistance, migration resistance, and electrical characteristics after moisture absorption. In view of the above, a polyfunctional cyanate resin composition is preferred.

The polyfunctional cyanate compound which is a preferred thermosetting resin component of the present invention is a compound having two or more cyanato groups in a molecule. Specific examples include 1,3- or 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-, 1,8-, 2 , 6- or 2,7-
Dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4-dicyanatobiphenyl, bis (4-dicyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, 2,2- Bis (3,5-dibromo-4-cyanatophenyl) propane, bis (4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) sulfone, tris (4-cy (Anatophenyl) phosphite, tris (4-cyanatophenyl) phosphate, and cyanates obtained by reacting novolak with cyanogen halide.

Other than these, Japanese Patent Publication Nos. 41-1928 and 43-1846
8, polyfunctional cyanate compounds described in JP-A-44-4791, JP-A-45-11712, JP-A-46-41112, JP-A-47-26853 and JP-A-51-63149 can also be used. Further, a prepolymer having a molecular weight of 400 to 6,000 and having a triazine ring formed by trimerization of a cyanato group of these polyfunctional cyanate compounds is used. This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate ester monomer with a catalyst such as acids such as mineral acids and Lewis acids; bases such as sodium alcoholate and tertiary amine; salts such as sodium carbonate and the like. Is obtained by The prepolymer also contains some unreacted monomers and is in the form of a mixture of the monomer and the prepolymer, and such a raw material is suitably used for the purpose of the present invention. Generally, it is used after being dissolved in a soluble organic solvent.

As the epoxy resin, a generally known epoxy resin can be used. Specifically, liquid or solid bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin; butadiene, pentadiene, vinylcyclohexene, dicyclopentyl ether, etc. And polyglycidyl compounds obtained by reacting a polyol, a hydroxyl-containing silicone resin with an epohalohydrin, and the like. These may be used alone or in combination of two or more.

As the polyimide resin, generally known ones can be used. Specific examples include a reaction product of a polyfunctional maleimide and a polyamine, and a polyimide having a terminal triple bond described in JP-B-57-005406. These thermosetting resins may be used alone, but it is preferable to use them in an appropriate combination in consideration of the balance of properties.

Various additives can be added to the thermosetting resin composition of the present invention, if desired, as long as the inherent properties of the composition are not impaired. These additives include polymerizable double bond-containing monomers such as unsaturated polyesters and prepolymers thereof; polybutadiene, epoxidized butadiene, maleated butadiene, butadiene-
Low molecular weight liquid to high molecular weight elastic rubbers such as acrylonitrile copolymer, polychloroprene, butadiene-styrene copolymer, polyisoprene, butyl rubber, fluororubber, natural rubber; polyethylene, polypropylene, polybutene, poly-4-methyl Penten, polystyrene, AS
Resin, ABS resin, MBS resin, styrene-isoprene rubber,
Polyethylene-propylene copolymer, 4-fluoroethylene-
6-fluorinated ethylene copolymers; high molecular weight prepolymers or oligomers such as polycarbonate, polyphenylene ether, polysulfone, polyester, and polyphenylene sulfide; and polyurethane are exemplified and used as appropriate. In addition, other known organic fillers, dyes,
Pigments, thickeners, lubricants, defoamers, dispersants, leveling agents,
Various additives such as a photosensitizer, a flame retardant, a brightener, a polymerization inhibitor, and a thixotropy-imparting agent are used in an appropriate combination as required. If necessary, the compound having a reactive group is appropriately blended with a curing agent and a catalyst.

As the copper-clad board used in the present invention, a thermosetting resin composition in which an insulating inorganic filler is suitably blended is used. Generally known ones can be used. Specifically, talc, calcined talc, wollastonite, kaolin, aluminum hydroxide, magnesium hydroxide, synthetic mica, silica, and various glass fiber powders, such as the flat glass fiber powder used in the present invention. Can be The compounding amount is 10 to 80% by weight, preferably 20 to 70% by weight in the total thermosetting resin composition. These are effective as a homogenizing agent for the resin composition layer on the pore wall when drilling with a carbon dioxide gas laser. The average particle diameter of 1 μm or less is preferably used.

The thermosetting resin composition of the present invention can be cured by heating itself, but has a low curing rate and is inferior in workability and economic efficiency. Can be used. The amount used is 0.005 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the thermosetting resin.

The auxiliary layer used in the present invention has a melting point of 900.
As the metal compound having a binding energy of 300 kJ / mol or more at a temperature of not less than ° C., generally known compounds can be used. Specifically, as the oxide, titania such as titanium oxide, magnesia such as magnesium oxide, nickel oxide such as nickel oxide, manganese dioxide, zinc oxide such as zinc oxide, silicon dioxide, aluminum oxide, Rare earth oxides, cobalt oxides such as cobalt oxide, tin oxides such as tin oxide, tungsten oxides such as tungsten oxide, and the like can be given. Examples of the non-oxide include generally known ones such as boron nitride, silicon nitride, titanium nitride, aluminum nitride, barium sulfate, and rare earth oxysulfide. In addition, various glass powders which are a mixture of metal oxide powders can be used. Carbon powder and metal powder such as silver, copper, iron and nickel can also be used, and these are used alone or in combination of two or more. The average particle size is not particularly limited, but is preferably 1 μm or less.

Since the molecules are dissociated or melted and scattered by the irradiation of the carbon dioxide gas laser, the metal adheres to the hole walls and the like, and does not adversely affect the semiconductor chip and the hole wall adhesion. preferable. Since Na, K, Cl ions and the like particularly adversely affect the reliability of the semiconductor, those containing these components are not suitable. The compounding amount is from 3 to 97% by volume, preferably from 5 to 95% by volume, and is mixed with the resin and uniformly dispersed.

The resin of the auxiliary layer is not particularly limited.
Generally known ones can be used, but if removed after drilling, they may adhere to the copper foil surface, and water-soluble resins are preferred. Specifically, a water-soluble polyester resin,
Polyether resin, polyvinyl alcohol, starch and the like are used. Also in this case, the various additives described above can be added.

The method of preparing the composition comprising the metal compound powder and the resin, and the method of forming a sheet are not particularly limited, but they are kneaded at a high temperature without a solvent using a kneader or the like, and extruded into a sheet on a thermoplastic film. The method of adhesion, the resin is dissolved in a solvent, the above powder is added to the mixture, and the mixture is uniformly stirred and mixed. The mixture is used as a coating and dried on a copper foil to form a coating or a thermoplastic film. A generally known method such as a method of forming a film by coating and drying on the surface can be used. The thickness is not particularly limited, but when applied, the thickness of the coating is preferably 30 to 100 μm, and when applied to a film to form a coating with a film, preferably including the thickness of the film. The total thickness should be 30 to 200 μm.

When laminating the copper foil surface under heating and pressure, the coating resin layer is directed to the copper foil surface, and the temperature is generally 40 to 150 ° C., preferably 60 to 120 ° C., and the linear pressure is generally
Lamination is performed under a pressure of 0.5 to 20 kgf, preferably 1 to 10 kgf, and the resin layer is melted and brought into close contact with the copper foil surface. The choice of lamination temperature depends on the melting point of the water-soluble resin used,
In general, lamination is performed at a temperature higher by 5 to 20 ° C. than the melting point of the resin, although it depends on the linear pressure and the laminating speed.

The metal oxide treatment applied to the inner layer, or the inner and outer copper foils to form a fine circuit is not particularly limited. For example, black copper oxide treatment, MM treatment (MacDer
mid company). For chemical treatment, CZ
A generally known treatment such as a treatment (Mec) can be used.

The substrate-reinforced copper clad board is first impregnated with a thermosetting resin composition into the above-mentioned reinforcing substrate and dried to form a B stage.
Create a prepreg. Next, a predetermined number of the prepregs are stacked, a copper foil is arranged on at least one side, and laminated under heat and pressure to form a copper-clad laminate. Further, a multi-layer board prepared by using this can also be used. The thickness of the outer layer copper foil is
Preferably, the thickness is 3 to 12 μm, and the thickness of the inner layer is 9 to 35 μm. The type of the copper foil is not particularly limited, but an electrolytic copper foil having a double-sided roughened foil can be used for the inner layer. Electrolytic copper foil is preferred for both the inner and outer layers. The method for etching and removing copper burrs generated in the holes according to the present invention is not particularly limited. For example, JP-A-02-2288
7, 02-22896, 02-25089, 02-25090, 02-5933
7, 02-60189, 02-166789, 03-25995, 03-6018
3, the method of dissolving and removing the metal surface with a chemical disclosed in JP 03-94491, JP 04-199592 and JP 04-263488 (SUE
P method). The etching rate is generally 0.02
Perform at ~ 1.0 µm / sec. Further, in the case of removing the inner layer copper foil burr by etching, the spray angle and pressure of the etching solution are appropriately selected. A method of removing burrs by suction may also be used.

The carbon dioxide laser is in the infrared wavelength range.
Wavelengths of 9.3 to 10.6 μm are commonly used. The energy of the carbon dioxide laser is preferably selected from 20 to 60 mJ / pulse. The required pulse (shot) of the high output energy carbon dioxide laser light is applied directly from above the auxiliary layer to process the copper foil and the insulating layer. And drill holes. When drilling through holes and / or blind via holes, 20 to 60 mJ /
Any method can be used, such as a method of irradiating an energy selected from a pulse, a method of forming a hole in a copper foil, and then increasing or decreasing the energy to process the insulating layer.

On the back surface of the copper-clad plate, it is possible to simply arrange a metal plate in order to prevent the laser machine table from being damaged by the laser when the hole penetrates. A resin layer to which at least a part is adhered is adhered to a copper foil on the back surface of the copper clad board, and a through hole is formed. When the front and back copper foils are thin, copper foil burrs generated around the holes are dissolved and removed with an etchant while leaving the front and back auxiliary layers after drilling. When the front and back copper foils are thick, the auxiliary layer is dissolved and removed first after drilling the through-hole, and then the etching liquid is sprayed on the entire surface to partially dissolve and remove the front and back copper foils in a planar manner. By removing the burrs and setting the thickness of the surface copper foil to 2 to 7 μm, a fine circuit can be formed in the subsequent formation of a copper-plated circuit, and a high-density printed wiring board can be produced.
The latter is preferred from the viewpoint of removing surface dirt and foreign matter. The same applies to the case of forming a via hole.

In most cases, a resin layer of about 1 μm is left on the surface of the copper foil surface on the surface of the inner surface of the processed copper foil where the resin is adhered. This resin layer can be removed in advance by a generally known treatment such as a desmear treatment before etching. However, when the liquid does not reach the inside of the small-diameter hole, a residue of the resin layer remaining on the surface of the copper foil in the inner layer may be left, resulting in poor connection with copper plating. Therefore,
More preferably, the inside of the hole is first treated in a gas phase to completely remove the residual layer of the resin, and then the inside of the hole and the copper burrs on the front and back surfaces are removed by etching. As the gas phase treatment, generally known treatments can be used, and examples thereof include a plasma treatment and a low-pressure ultraviolet treatment. As the plasma, low-temperature plasma in which molecules are partially excited by a high-frequency power source and ionized is used. For this, high-speed processing using ion bombardment and gentle processing using radical species are generally used, and reactive gases and inert gases are used as processing gases. As the reactive gas, oxygen is mainly used, and the surface is chemically treated. As the inert gas, an argon gas is mainly used. Using this argon gas or the like, physical surface treatment is performed. Physical treatment uses ion bombardment to clean the surface. The low ultraviolet ray is an ultraviolet ray having a short wavelength region, and irradiates a short wavelength region having a peak at 184.9 nm and 253.7 nm, and decomposes and removes the resin layer.
The inside of the hole can be subjected to normal copper plating,
Further, the inside of the hole can be partially filled with copper plating, preferably at least 80% by volume.

[0031]

The present invention will be specifically described below with reference to examples and comparative examples. Unless otherwise specified, “parts” indicates parts by weight.

Example 1 900 parts of 2,2-bis (4-cyanatophenyl) propane,
100 parts of (maleimidophenyl) methane are melted at 150 ° C,
The mixture was reacted for 4 hours with stirring to obtain a prepolymer. This was dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide. Add bisphenol A type epoxy resin (trade name: Epicoat 1001, Yuka Shell Epoxy Co., Ltd.)
) And 600 parts of a cresol novolac type epoxy resin (trade name: ESCN-220F, manufactured by Sumitomo Chemical Co., Ltd.) were uniformly mixed and dissolved. Further, as a catalyst, zinc octylate 0.4
Were added and dissolved and mixed. To this, 2,000 parts of an inorganic filler (trade name: calcined talc, average particle size 0.9 μm) and 8 parts of a black pigment were added, and uniformly stirred and mixed to obtain Varnish A. This varnish was impregnated into a glass woven fabric having a thickness of 100 μm using ordinary glass fiber having a circular cross section, dried at 150 ° C., and gelled for at gel time (at 170
C) for 120 seconds to prepare a prepreg B having a glass content of 50% by weight. In addition, thickness 62μm, aspect ratio is 4/1, area ratio is 92%
In the above, a flat glass fiber having a reduced fiber diameter of 10 μm and a length of 13 mm was dispersed in a polyethylene oxide dispersion solution, and an epoxy resin emulsion and silane coupling were applied to a nonwoven fabric that was formed so that the basis weight was 20 g / m ^2. Make an adhesive solution using epoxy silane coupling agent as
% By weight and dried at 150 ° C. to obtain a nonwoven fabric. Using this, the varnish A was impregnated and dried to adhere a resin amount of 81% by weight to prepare a prepreg C having a gelation time of 86 seconds.

An electrolytic copper foil having a thickness of 12 μm was placed above and below the two prepregs B and laminated and formed at 200 ° C., 20 kgf / cm ² , and a vacuum of 30 mmHg or less for 2 hours. Obtained. An inner layer circuit was formed, the surface thereof was subjected to CZ treatment (MEC Corporation), and an electrolytic copper foil having a thickness of 12 μm was disposed on both outer sides thereof.

On the other hand, MgO (54%), SiO ₂
To a varnish prepared by dissolving a water-soluble polyester resin in a mixed solvent of water and methanol, to 800 parts of a mixture powder (average particle size: 0.9 μm) consisting of
Got F. This was applied to one side of a 50 μm-thick polyethylene terephthalate so as to have a thickness of 20 μm.
After drying for minutes, an auxiliary material layer having a metal compound content of 40 vol% was prepared, and an auxiliary material G was obtained. On the back surface, the varnish F was applied to one surface of an aluminum foil having a thickness of 50 μm, and dried similarly to prepare a backup sheet H having a coating film having a thickness of 20 μm. The auxiliary material G is disposed on the front surface of the four-layer plate E, the backup sheet H is disposed on the back surface, and the resin layer is disposed so as to face the copper foil side. Laminated. From above, with a carbon dioxide laser machine, 900 holes with a diameter of 100 μm are directly 900 in a 50 mm square, 1 shot at 25 mJ / pulse first, then 10 mJ / pulse at output 25 mJ / pulse, then one shot. Three
One shot was irradiated at 0 mJ / pulse, and a via hole with a hole diameter of 100 μm was formed. One shot at 30 mJ / pulse, 25 mJ / pulse
By irradiating 5 shots with a pulse, a through hole having a hole diameter of 120 μm was formed.

After the auxiliary material layers of the front and back layers are separated and put into a plasma apparatus for processing, a SUEP solution is sprayed at a high speed to dissolve and remove burrs on the front and back and the inner layer, and simultaneously, the copper foil of the front layer is reduced to 4 μm. Dissolved. After desmearing, deposit copper plating 15μm, and then use the existing method (line / line).
Space = 50/50 μm). After forming a circuit on the front and back sides and performing CZ treatment, one prepreg C was similarly placed on each side, and a 12 μm electrolytic copper foil was placed on the outside of the prepreg C, and laminated and formed in the same manner to form a six-layer plate. A hole-forming auxiliary material was similarly arranged on the front and back sides, and after bonding, a via hole was formed by pulse oscillation of a carbon dioxide laser under the same conditions, and a through-hole was formed. After that, the front and back auxiliary materials are peeled off, and the thickness of the front and back is 4
At the same time as dissolving and removing up to μm, the copper foil burr was also dissolved and removed. Form circuits such as solder ball pads on the front and back, and cover with plating resist except for at least the semiconductor chip part, bonding pad part, solder ball pad part,
Nickel and gold plating were applied to make a printed wiring board. Tables 1 and 2 show the evaluation results of this printed wiring board.

Example 2 Epoxy resin (trade name: Epicoat 1001, manufactured by Yuka Shell Epoxy Co., Ltd.), 300 parts, and epoxy resin (trade name: ESC
N220F, manufactured by Sumitomo Chemical Co., Ltd.) 700 parts, dicyandiamide
35 parts, 1 part of 2-ethyl-4-methylimidazole was dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide,
Varnish I was obtained by uniformly stirring and mixing. On the other hand, the aspect ratio 4/1,
Using a fiber having an area ratio of 94% and a fiber diameter of 13 μm, the paper was made in the same manner as in Example 1, impregnated so that the solid content became 7% by weight, and dried in the same manner to obtain a basis weight of 21 g / m ^2. Was obtained. Using this glass fiber nonwoven fabric, impregnated with varnish I,
After drying, a prepreg J having a gelling time of 120 seconds and a resin amount of 46% by weight and a prepreg K having a gelling time of 110 seconds and a resin amount of 78% by weight were obtained.

Using the four prepregs J, 12
A μm electrolytic copper foil was placed and laminated and formed at 190 ° C., 20 kgf / cm ² and 30 mmHg to obtain a double-sided copper-clad laminate L (FIG. 2 (1)). Circuits are formed on the front and back of this board, and MM processing (MacDerm
id company), put one prepreg K on the outside, put 3μm electrolytic copper foil with 35μm copper foil carrier on the outside, peel off the 35μm copper foil carrier after laminating similarly, A four-layer plate M was prepared (FIG. 2 (2)).

On both surfaces, a mixture of the transparent acrylic acid resin having an acid value of 100 mgKOH / g and the metal compound of Example 1 was applied, and dried at 120 ° C. for 20 minutes to obtain a 30 μm thick film.
A coating of 65% by volume of the metal compound was formed. Thickness on this back
A 50 μm aluminum foil was placed, the target mark was read using the same carbon dioxide laser device as in Example 1, and the carbon dioxide laser was similarly shot at 30 mJ / pulse for one shot at 28 mJ / pulse.
Irradiate 4 shots with pulse, through hole of 120μm diameter, 1 shot with 20mJ / pulse, 1 shot with 10mJ / pulse, and 1 shot with 30mJ / pulse, and hole diameter 100
A μm blind via hole was made (FIG. 2 (3)). Copper foil burrs remaining around the holes were dissolved and removed with an acidic etching solution, leaving the front and back auxiliary resin layers, and then the front and back auxiliary layers were dissolved and removed with an alkaline aqueous solution. A desmear treatment was performed with an aqueous solution of potassium permanganate (FIG. 2 (4)), copper plating was similarly performed (FIG. 3 (5)), and a printed wiring board was similarly formed, and solder balls were attached (FIG. 3). (6)). The evaluation results are shown in Tables 1 and 2.

COMPARATIVE EXAMPLE 1 Using the copper clad board of Example 1, a hole was similarly formed with a carbon dioxide gas laser without attaching anything to the surface, but no hole was formed.

Comparative Example 2 In Example 2, the surface to be irradiated with the carbon dioxide gas laser was coated on the copper foil surface with black magic, and a hole was formed in the same manner, but no hole was formed.

Comparative Example 3 Glass fibers having an elliptical approximate cross-section with an aspect ratio of 4/1 and an area ratio of 75%, a reduced fiber diameter of 10 μm, and a length of 13 mm were used. Prepreg N was prepared under the same conditions as in Example 2 except that the prepreg was impregnated so as to be 8% by weight. Using this, a laminate was formed in the same manner, and a hole was formed in the same manner to obtain a printed wiring board. SUEP was not implemented. The evaluation results are shown in Tables 1 and 2.

Comparative Example 4 In Example 2, epicoat 5045 was used as an epoxy resin.
1000 parts and a glass fiber of # 1080 type (weight 48g / m ² ) using circular fiber as glass fiber, resin amount 70
The prepreg O having a gelation time of 116 seconds was obtained by impregnating and drying to give a weight%. Further, a glass fiber woven fabric having a thickness of 100 μm was impregnated and dried to prepare a prepreg P having a gelation time of 122 seconds and a resin amount of 45% by weight. Use two prepregs P,
Laminate molding was performed at 175 ° C. and 20 kgf / cm ² for 2 hours to prepare a double-sided copper-clad laminate. After forming a circuit on both sides and subjecting it to black copper oxide treatment, one prepreg O is placed on each side,
Laminate molding was performed under the same conditions to obtain a four-layer plate Q. Using this, a mechanical drill with a drill diameter of 150 μm, rotation speed 100,000 rpm
Similarly, through holes were made at 400 μ intervals. A desmear treatment was performed once without performing the SUEP treatment, and thereafter, copper plating was performed by a normal method to prepare a printed wiring board. The evaluation results are shown in Tables 1 and 2.

COMPARATIVE EXAMPLE 5 In Example 2, a double-sided copper-clad laminate L (FIG. 4A) was used, and the copper foil at a location to be a through hole in the inner layer was formed with a hole diameter of 100.
After removing the upper and lower copper foil by etching to form a circuit, and forming a circuit, the surface of the copper foil was treated with black copper oxide, and one prepreg K was placed on the outside thereof, and a 12 μm electrolytic copper foil was placed on the outside. It arrange | positioned and laminated | stacked similarly, and produced the four-layer board. Using this multilayer plate, a hole diameter of 10
900 holes of 0 μm were formed by etching a copper foil. Similarly, 900 holes having a hole diameter of 100 μm were formed at the same position on the back surface (FIG. 4B). 70 blocks of 900 patterns per pattern, total 6
3,000 holes from the surface with carbon dioxide laser, output 15mJ /
Six shots were made with a pulse, and a through hole was made (Fig. 4
(3)). After that, in the same manner as in Comparative Example 4, without performing the SUEP treatment, a desmear treatment was performed once, copper plating was performed 15 μm (FIG. 4 (4)), circuits were formed on the front and back surfaces, and a printed wiring board was similarly formed. Created. The evaluation results are shown in Tables 1 and 2.

[0044]

[Table 1]

[0045]

[Table 2]

<Measurement Method> 1) Clearance between the front and back holes, deviation from the hole wall of the inner copper foil, and drilling time Within a 250 mm square work size, 70 blocks with a hole diameter of 100 μm were set as 900 holes / block (hole meter). 63,000 holes). The time required to make 63,000 holes in one copper clad board, the gap between the copper foil for front and back lands and the hole, and the maximum value of the deviation of the inner layer copper foil were determined by drilling holes with a carbon dioxide laser and a mechanical drill. Indicated. 2) Hole wall irregularities The hole cross section was observed. 3) Circuit pattern breakage and short circuit In Examples and Comparative Examples, plates without holes were created in the same manner, and a comb pattern of line / space = 50/50 μm was created. Observation was made with the naked eye, and the total of the cut pattern and the short-circuited pattern was shown in the molecule. 4) Glass transition temperature Measured by the DMA method. 5) Through hole heat cycle test Create a land diameter of 250 μm for each through hole hole, connect 900 holes alternately front and back, one cycle is 260 ° C, solder, immersion 30 seconds → room temperature, 5 minutes, up to 500 cycles The maximum value of the rate of change of the resistance value was shown. 6) Migration resistance (HAST) A total of 50 holes are connected without passing one through hole with a hole diameter of 100 μm or 150 μm (mechanical drill) alternately.
Make a total of 100 sets so that they are parallel
After a predetermined time treatment at 30 ° C., 85% RH, and 1.8 VDC, the samples were taken out and the insulation resistance between through holes arranged in parallel was measured. 7) Surface smoothness Measured with a surface roughness meter.

[0047]

According to the present invention, a copper-clad laminate using a glass woven or non-woven fabric for the inner layer is used, a circuit is formed on at least one side thereof, and a chemical treatment is performed as required. The flatness expressed by the major axis / minor axis of the cross section is 3.1 / 1
The cross-sectional area is 90 to 98% of the area of the rectangle circumscribing the glass fiber cross section, and the converted fiber diameter is 5 to 17μ.
Multilayer copper clad obtained by laminating and forming a prepreg based on a glass fiber nonwoven fabric having a flat glass fiber of 90% by weight or more and a binder amount of 3 to 8% by weight for build-up. A method for forming holes in a plate is provided. The multilayer copper-clad board used in the present invention has excellent surface smoothness, can reduce the thickness of the glass layer, and at the same time, can increase the density of the glass fiber. Suitable for drilling. Preferably, 20-60mJ /
Forming an auxiliary layer on the copper foil surface and then directly irradiating the copper foil with the pulsed carbon dioxide laser energy to form through holes and / or blind via holes with less unevenness on the hole wall. Can be. The through holes and / or blind via holes formed by the method of the present invention have no gap between the holes on the front and back of the copper clad board and the land copper foil, and the processing speed is remarkably faster as compared with drilling with a mechanical drill. ,
Excellent hole position accuracy and significant improvement in productivity. In addition, by using a thin copper foil with a thickness of 2 to 7 μm as the front and back layer copper foil, defects such as short circuit and pattern breakage may occur even in the circuit formation of the front and back copper foil obtained by plating up with subsequent copper plating. Thus, a high-density printed wiring board could be produced without any problem, and a product having excellent reliability could be obtained. Furthermore, by using a polyfunctional cyanate ester resin composition as the thermosetting resin composition, the resulting printed wiring board was obtained with excellent heat resistance, migration resistance, and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flat glass fiber.

[FIG. 2] Drilling through holes and blind via holes by a carbon dioxide laser using the multilayer copper-clad board of Example 2 (3), SU
It is a process figure of burr removal (4) by EP.

FIG. 3 is a process diagram of copper plating (5), coating with a plating resist, nickel plating, gold plating and solder ball bonding (6) of a multilayer copper-clad board of Example 2 with a carbon dioxide gas laser.

FIG. 4 is a process drawing of drilling and copper plating of a multilayer copper-clad board of Comparative Example 5 with a carbon dioxide gas laser (without SUEP).

[Explanation of symbols]

 a Double-sided copper-clad board G b Four-layer copper-clad board c Inner-layer copper foil circuit d Thermosetting resin composition layer of glass nonwoven fabric base e Carbon dioxide laser drilling auxiliary layer f Carbon dioxide laser drilled through-hole g Carbon dioxide laser H Copper foil burrs of outer layer via holes generated i Copper foil burrs of outer layer through holes generated j Via holes with burrs removed by SUEP k Through holes with burrs removed by SUEP l Copper Plated via hole m Copper-plated through hole n Plated resist o Solder ball p Inner layer copper foil with misalignment q Copper plating of through hole with poor drilling r Surface layer copper foil circuit s Carbon dioxide gas laser hole Inner layer copper burrs generated by drilling

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/00 H05K 3/00 N 3/42 610 3/42 610A // B23K 101: 42 B23K 101: 42 F-term (reference) 4E068 AF01 DA11 5E317 AA24 BB01 BB02 BB03 BB12 CC31 CD05 CD11 CD25 CD27 CD32 GG14 GG16 5E346 AA06 AA12 AA15 AA26 AA29 AA32 AA35 AA42 AA43 AA54 CC02 CC04 CC08 CC09 CC10 EE13 EE DD DD EE CC FF03 FF07 GG15 GG16 GG17 GG22 GG25 GG27 GG28 HH26 HH33

Claims (6)

[Claims] 1. A glass fiber having a flat cross section, a flattening ratio expressed by a major axis / a minor axis of the cross section being 3.1 / 1 to 5/1, and a cross sectional area of a rectangular shape circumscribing the glass fiber cross section. Area
90 to 98%, the converted fiber diameter contains 5 to 17 μm flat glass fiber 90 wt% or more, and the amount of the binder is 3 to 8
By weight, the surface of a multilayer copper-clad board for a build-up multilayer printed wiring board having a layer in which a thermosetting resin composition is adhered to a glass fiber nonwoven fabric substrate having a thickness of 100 μm or less, at least on the surface side. A carbon dioxide gas laser drilling auxiliary layer, and directly irradiating a carbon dioxide gas laser having sufficient energy to process the copper foil from above to form through holes and / or blind via holes. Of forming holes in a build-up multilayer printed wiring board. 2. The method for forming holes in a build-up multilayer printed wiring board according to claim 1, wherein an insulating inorganic filler is blended in the thermosetting resin composition in an amount of 10 to 80% by weight. 3. The hole formation of a build-up multilayer printed wiring board according to claim 1, wherein the thermosetting resin is a resin composition containing a polyfunctional cyanate ester compound and the cyanate ester prepolymer as essential components. Method. 4. On a multilayer copper-clad board, at a melting point of 900 ° C. or more,
In addition, a metal compound having a binding energy of 300 kJ / mol or more, a carbon powder, or a hole-forming auxiliary layer in which one or more kinds of metal powders are mixed in an organic compound is disposed, and carbon dioxide having sufficient energy to process a copper foil is provided. 4. The method for forming a hole in a build-up multilayer printed wiring board according to claim 1, wherein a through hole and / or a blind via hole is made by directly irradiating a gas laser. 5. A metal oxide treatment or a chemical treatment is applied to the multilayer copper-clad board, and a carbon dioxide gas laser having sufficient energy to process the copper foil is directly irradiated from the metal oxide treatment or the chemical treatment.
4. A method for forming a hole in a build-up multilayer printed wiring board according to claim 1, wherein a blind via hole is formed. 6. The method is characterized in that after forming a carbon dioxide gas laser hole, a part of the thickness of the surface layer copper foil is dissolved and removed with a chemical solution, and at the same time, copper foil burrs generated around the hole are dissolved and removed. The method for forming a hole in a build-up multilayer printed wiring board according to claim 1, 2, 3, 4, or 5.